Numerical evaluation of RCCI engine performance under fuel aggregation strike to piston bowl rim-edge condition

To improve the homogenization process of the air-fuel mixture inside the combustion chamber as well as controlling the ignition time in a Reactivity Controlled Compression Ignition (RCCI) engine, changing the start of injection timing of the fuel is important. When the start of injection timing changes, at certain crank angels the fuel may collide with the bowl rim edge. In this condition, some unwanted fluid flow phenomena may happen that affect the air-fuel mixing process and prevent the homogenization of fuel and air, this can disrupt the fuel combustion process .In this study, at first, the SOI range in which the fuel collides with the piston bowl rim edge was recognized (between 44OCA bTDC and 54OCA bTDC) and the engine performance and emission production were examined in the start and end of this SOI range. For validation of the numerical results, these results were compared to the experimental data. The numerical results show that in the SOI timing of 44OCA bTDC, the maximum in-cylinder mean pressure and nitrogen oxides emission are more than 54OCA bTDC, however, the unburnt hydrocarbons and ignition delay are lower in this SOI timing. On the other hand influence of changing the air-fuel mixture temperature on the engine performance in this special condition was also evaluated. It was observed that increasing the IVC temperature leads to higher in-cylinder pressure and indicated mean effective pressures. Furthermore, by raising the IVC temperature, NOx emission increases insignificantly, while carbon monoxide and unburnt hydrocarbons are considerably decreased.

Numerical evaluation of RCCI engine performance under fuel aggregation strike to piston bowl rim-edge condition Keywords:

RCCI , piston bowl rim edge , IVC temperature , Nox